Integrated circuits (ICs) such as Programmable Logic Devices (PLDs), including Field Programmable Gate Arrays (FPGAs), require some form of “power up reset” (PUR) detector. The PUR detector informs the IC when to start configuration and/or resetting of its registers. The PUR detector provides a signal to the IC informing it that the supply voltage to the IC has reached an acceptable level after the IC is powered up.
Typically, a band-gap regulated PUR is used to determine when the main power (supply voltage) of the IC is high enough to start configuration and/or resetting of the IC registers after a reset or power-up condition has occurred. Although useful, a band-gap regulated PUR circuit has several disadvantages, mainly it consumes a lot of power. It also needs to use precisely manufactured diodes and resistors since it requires tight component tolerances to function properly.
With the need in the electronics industry for lower power consumption and lower voltage ICs to support such areas as portable communication devices and portable computers, a need exists in the art for a power-up reset and/or brownout detector circuit that can operate at lower voltages and consume less power than some of the previous PUR circuits.